Basic Cisco Router Configuration Commands

Set a console password to cisco
Router(config)#line con 0
Router(config-line)#login
Router(config-line)#password cisco

Set a telnet password
Router(config)#line vty 0 4
Router(config-line)#login
Router(config-line)#password cisco

Stop console timing out
Router(config)#line con 0
Router(config-line)#exec-timeout 0 0
Set the enable password to cisco
Router(config)#enable password cisco

Set the enable secret password to certs.
This password overrides the enable password and is encypted within the config file
Router(config)#enable secret certs

Enable an interface
Router(config-if)#no shutdown

To disable an interface
Router(config-if)#shutdown

Set the clock rate for a router with a DCE cable to 64K
Router(config-if)clock rate 64000

Set a logical bandwidth assignment of 64K to the serial interface
Router(config-if)bandwidth 64
Note that the zeroes are not missing

To add an IP address to an interface
Router(config-if)#ip address 192.168.1.1 255.255.255.0

To enable RIP on all 192.168.x.y interfaces
Router(config)#router ripRouter(config-router)#network 192.168.0.0

Disable RIP
Router(config)#no router rip

To enable IRGP with a AS of 200, to all interfaces
Router(config)#router igrp 200
Router(config-router)#network 172.16.0.0

Disable IGRP
Router(config)#no router igrp 200

Static route the remote network is 172.16.1.0, with a mask of 255.255.255.0, the next hop is 172.16.2.1, at a cost of 5 hops
Router(config)#ip route 172.16.1.0 255.255.255.0 172.16.2.1 5

Disable CDP for the whole router
Router(config)#no cdp run

Enable CDP for the whole router
Router(config)#cdp runDisable CDP on an interface
Router(config-if)#no cdp enable

Cisco Modes of Operation

The Cisco IOS software provides access to several different command modes. Each command mode provides a different group of related commands.
For security purposes, the Cisco IOS software provides two levels of access to commands: user and privileged. The unprivileged user mode is called user EXEC mode. The privileged mode is called privileged EXEC mode and requires a password. The commands available in user EXEC mode are a subset of the commands available in privileged EXEC mode.
The following table describes some of the most commonly used modes, how to enter the modes, and the resulting prompts. The prompt helps you identify which mode you are in and, therefore, which commands are available to you.

User EXEC Mode:
When you are connected to the router, you are started in user EXEC mode. The user EXEC commands are a subset of the privileged EXEC commands.

Privileged EXEC Mode:
Privileged commands include the following:
• Configure – Changes the software configuration.
• Debug – Display process and hardware event messages.
• Setup – Enter configuration information at the prompts.

Enter the command disable to exit from the privileged EXEC mode and return to user EXEC mode.

Configuration Mode
Configuration mode has a set of submodes that you use for modifying interface settings, routing protocol settings, line settings, and so forth. Use caution with configuration mode because all changes you enter take effect immediately.

To enter configuration mode, enter the command configure terminal and exit by pressing Ctrl-Z.

Note: Almost every configuration command also has a no form. In general, use the no form to disable a feature or function. Use the command without the keyword no to re-enable a disabled feature or to enable a feature that is disabled by default. For example, IP routing is enabled by default. To disable IP routing, enter the no ip routing command and enter ip routing to re-enable it.